Hydraulically actuated surface equipment for pumps



July 31, 1956 R. H. DElTRiCKSON HYDRAULICALLY ACTUATED SURFACE EQUIPMENTFOR PUMPS 2 Sheets-Sheet 1 Filed May 11, 1953 J L w grwc/n'tm Roy H.De/fri (A1500 \iiiik y 1, 1956 R. H. DEITRICKSON 2,756,562

HYDRAULICALLY ACTUATED SURFACE EQUIPMENT FOR PUMPS 2 Sheets-Sheet 2 29mine 30 Ii ,7 3

Filed May 11, 1953 HEAT EXCHANGE! WATER L l N E5 COM OIL LEVEL (MAX)?PILOT VALVE 5/ 45 UIO DUMP VALVE PUMPING JACK AIR PRESSURE 5 54 37CONTROLS SHAFT 5 N l s r i eme To MR COMPRESSOR Roy H. Oeifric/rson2,756,562 Patented July 31, 1956 HY DRAULICALLY ACTUATED'SUR'FACEEQUIPMENT FOR PUMPS Roy H. Deitrickson, Toledo, Ohio, assignor to TheNational Supply Company, Pittsburgh, Pa., a corporation of PennsylvaniaApplication May 11, 1953, Serial No. 354,167

8 Claims. (Cl; 60-52) This invention relates to hydraulically actuatedsurface equipment for pumps of the type frequently used I der or pumpingjack in which'th'ere is located a piston that is connected toa pumprod-which usually extends downwardly from the pumping jack andisoperatively linked to the sucker rod' string extending down to thepump itself at the production area level. A hydraulic system for theintroduction of working fluid under high pressure into the pumping jackto force the piston upwardly usually includes a mainpump and'ar-r enginefor driving the pump, a sump for'provi'ding supply of working fluid, aso-called e'ounterbalanci'rrg tank irrwhi'ch a volume of working fluidiskept under pressure for the storage of energy so that the load on thepump engine can be kept relatively constant duri'ng'both up anddownstrokes and the necessary controls, valves and hydraulic lines properlyto connect one part of the apparatus with the others.

In a system of this general type various control means must be providedfor automatically controlling the connections between the variouselements, the operation-of the pump, and the proper pressures and?volumes of both the working fluid and air within the system.

The instant invention: has as its principal object the provision of anautomatic fluid level control associated with the counterbalanci-ngtan'kt'o prevent'the' accumulation of an excessive amount'of workingfluid .wi'thin the tank and to compensate for leakage of: suchfl-uidfrom the system and for the purpose of. recirculation, filtering,cooling and cleaning of the oil. In the instant system, a scavengingpump is used which has suction side connected either to the sump or tothe: counterbal'ancing, tank depending on the level of fluid. in. the:latter.

It is another object of theinstant invention to provide a hydraulicsystem. wherein the working fluid. is constantly recirculated. through.filters andheat exchangers and other cleaning and treating apparatusesto: keep it in the proper condition and which 'hasautomatic' means forpreventing the accumulation of too large a quantity of such fluid withinthe energy-storing; counter-balancing tank.

It is yet another object. of this invention to provide apparatus bywhich a balance of pressure between the pressure of air in thecounterbalancing tank and the pressure of this air plus: the weight of acolumn of fluid is automatically utilized to control the volume ofworking fluid in the tank, and the invention comprises a novel valve forthis purpose.

Other and more specific objects and advantages of the invention will bebetter understood from thespecification which follows and fromthedrawings inwhich:

Fig. 1 is a simplified view, in elevation and on a very small scale, ofa surface hydraulic apparatuslfor actuatingthe sucker rod of aproductionpump, certain parts being shown in section.

Fig. 2 is a schematic hydraulic diagram of the main apparatus and linesconstituting a surface hydraulic sys temand in particular illustratingthe portion of the apparatus embodying the instant invention forautomatic fluid level control.

A surface hydraulic system embodying the invention includes a number ofconventional structures, the operation of which the invention isdesigned to facilitate. A surface hydraulic apparatus is designed forthe purpose of actuating a piston 10 in its pumping jack 11 which may beerected upon suitable framework 12 extending vertically above a casing13 of a well. A sucker rod 14 is attached to the piston 10 and extendsdown the casing 13 where it is connected to the plunger of a pump (notshown) located in the production area of the well. The pumping jack 11is connected by a main pump line 15 to amain pump 16. The line 15 may beprovided with an accumulator pipe 17 (see Fig. l-not shown in Fig. 2)for the purpose of reducing the peak sucker rod stresses by absorbingpulsations in the power fluid beneath the piston 10.

The pump 16 is driven by a shaft 18 (Fig. 2) extending through a shafttunnel 19 (Fig. l) and connected by suitable clutch means (not shown) toan engine 20.

The pump 16 also is connected by a main tank line 21 to the bottom of acounterbalancing tank generally indicated at 22'. The counterbalancingtank 22 is mounted upon legs 23 and provided with a shut oif valve 24.

In addition: to the main pump 16 the present system includes aconstantly driven scavenging pump 25 which "is connected by a scavengingpump output line 26 through an oil filter 27 and heat exchanger 28 to atank return line 29. The'tank return line 29 is attached to a spraynozzle 30 located at the top of the tank 22 and through which workingfluid returned to the tank by the scavengin-g pump 25 is sprayed ontothe interior surface of the tank 22. Spraying the working fluid onto theinterior surface of the tank 22 at its top provides for thorough washingover the surface of the tank 22 so that the rust and oxidationinhibitors introduced into the working fluid may prevent corrosion andcondensation on the inner surfaces of the tank 22.

The scavenging pump 25 has an input line 31 which is connected throughan upwardly openable check valve 32 to a main sump 33. The top of thepumping jack 11 also is connected by a line 34 to the sump 33 so thatleakage past the jack piston is returned to the sump. Since thehydraulic system operates under a substantial pressure as hereinafterdescribed, leakage is bound to occur at various points, and it is thefunction of the scavenging pump to make up for these losses.

An air compressor 35 is connected by a line 36 to the upper portion ofthe tank 22 and functions to maintain pressure within the tank 22.

In general, the apparatus operates as follows: During an up stroke thepressure maintained within the tank 22 forces working fiuid through theline 21 to the main pump 16. The pump 16 raises the pressure on thefluid and pumps it through the main line 15 into the pumping' jack 11.The high. pressure working fluid thus introduced into the pumping jack11 beneath the piston 10- raises the piston 10 lifting the sucker rod 14and the column of production fluid located in the casing 13 or in thetubing (not shown) within the casing 13 and delivering a quantity of theproduction fluid to the top of the well and to the production fluidmanifold (not shown) whence it is led to storage or further treatment.

Upon the completion of an up stroke caused by the introduction of highpressure working fluid beneath the pumping jack piston 10, suitablereversing valves are actuated and the fluid within the pumping jack 11flows back through the main line 15 to the main pump 16 and then withhigher pressure added by the main pump 16 is pumped back into thecounterbalancing tank 22.

By suitable air pressure control means generally indicated at 37 in Fig.2 and connected to the tank 22 by an air pressure control line 33, theair pressure within the tank 22 is maintained at a desired level bycontrolling the operation of the air compressor 35. The pressure withinthe tank 22 is calculated according to the equation P P r+2 c thepressure to be supplied by the counterbalancing tank. Using thesefigures, the air pressure control means 37 is so adjusted as to controlthe air compressor 35 to maintain an average pressure of 400 p. s. i. inthe tank 22.

On the up stroke the 400 p. s. i. pressure provided by the tank 22 isadded to the additional pressure provided by the main pump 16 in orderto overcome the 200 p. s. i. pressure of the sucker rod 14 and the 400p. s .i. pressure of the column of production fluid, a total of 600 p.s. i. Therefore, the main pump 16 must supply a pressure of 200 p. s. i.On the down stroke the weight of the sucker rod 14 causes a 200 p. s. i.pressure on the input side of the pump 16 and the pump must again add200 p. s. i. in order to pump the fluid back into the tank 22, the tankpressure being maintained at 400 p. s. i. Thus energy is stored in thetank 22 on the down stroke by the action of the pump and extracted toassist the pump 16 in performing the work of the up stroke.

In the present system, during such operation the scavenging pump 25 alsois constantly pumping to draw make-up working fluid from the sump 33through the check valve 32 to pump it through the output line 26, oilfilter 2'7 and heat exchanger 28 to the tank line 29 and into the tank22. While the scavenging pump 25 delivers a higher pressure than thepressure within the tank 22 so that the make up fluid can be introducedinto the tank 22, the volume delivered by the scavenging pump isrelatively small. It produces, however, a recirculation of all of thefluid in the system thus filtering and cooling the fluid to keep it ingood condition.

When, as frequently occurs, the scavenging pump has been pumping fluidinto the tank 22 continually for some time the level of working fluidwithin the tank 22 may rise above a maximum desired level. Apparatusembodying the instant invention is designed to prevent the level ofworking fluid from reaching a point above such a desired maximum. Itwill be appreciated that the level of fluid in the counterbalancing tankis constantly moving up and down and the liquid therein is highlyagitated due to the rapidity with which it is withdrawn and returned.Thus, ordinary liquid level controls are inadequate to determine themaximum fluid level, and some device not subject to the rapid andturbulent fluctuations must be used.

A working fluid level sensing pipe 39 is connected to the tank 22 at themaximum fluid level. The line 39 extends downwardly in order to providefor a head of fluid in the pipe 39 and is connected to a fluid levelpilot valve generally indicated at 40 leading to a chamber 41 beneath apressure responsive member such as a diaphragm 42. The chamber 41beneath the diaphragm 42 communicates through a port 43 with a pocket 44in the bottom of the pilot valve 40. The pocket 44 is connected to aline 45. Any suitable diaphragm actuated valve such as a plunger 46extending downwardly from the diaphragm 42 and into the pocket 44 mayserve as a valve for the line 45.

In the preferred form, a chamber 47 above the diaphragm 42 is connectedby a short line 48 to the air line 38 leading to the tank 22 so that thepressure on the upper side of the diaphragm corresponds to the pressurein the tank. The line 48 may be so designed as to constitute a trap inorder to prevent droplets of working fluid carried out of the tankthrough the air line 38 from accumulating in the chamber 47 above thediaphragm 42.

Air pressure within the tank 22 thus is applied to the upper side of thediaphragm 42 holding the valve plunger 46 down in valve closing positionand preventing the flow of any fluid out of the lower chamber 41 intothe line 45. A small coil spring 49 may be placed above the diaphragm 42in order to add its thrust to the pressure of the air in the line 38 tohold the diaphragm 42 and the plunger 46 down. There is, in addition apressure down on valve 46 due to the differential area created by theseated valve, the pressure being equal to the area of the valve timesthe air pressure on the diaphragm (which air pressure is the same onboth the upper and lower sides).

When the level of working fluid within the tank 22 reaches the point ofconnection of the pipe 39, the pipe 39 is filled with the Working fluid.The pressure created by the head of fluid is added to the pressurewithin the tank 22 (also present in the lines 38 and 48 and above thediaphragm 42) and, being applied beneath the diaphragm 42, it moves thediaphragm 42 upwardly lifting its valve plunger 46 and opening the line45. The working fluid in the line 39 flows into the line 45 and into afluid dump valve 50 beneath a valve piston 51 lifting the piston 51 andits plunger 52 to place a tank branch line 53 in communication with ascavenging pump intake branch line 54. When these two lines are placedin communication the constantly operating scavenging pump now withdrawsWorking fluid from the main line 21 and pumps it directly into thescavenging pump output line 26 and the upper tank input line 29. Thepresence of the working fluid in the line 54 at the counterbalancingtank pressure closes the check valve 32 and no additional fluid iswithdrawn from the sump 33 while the fluid dump valve 50 is open; thefluid in the tank 22 being directly recirculated.

This direct recirculation of fluid out of and into the counterbalancingtank 22 by the scavenging pump 25 continues as long as the maximum levelof working fluid in the tank 22 remains above the connection point ofthe fluid level sensing line 39 so that fluid can flow into the pipe 39.When an up stroke of the pumping jack, for example, causes thewithdrawal of a sufficient quantity of working fluid from the tank 22 tolower the working fluid level, no further working fluid flows into theline 32 and the head of fluid in the line 39 alone holds the pilot valve40 open so that the valve 40 does not operate at each stroke. During allof the time when the pilot valve 40 is held open fluid is bled from theline 45 through a bleeder valve 55 directly to a sump line 56. Duringthis time also leakage is occurring in the remainder of the system andis not being made up by the scavenging pump. Therefore, when the levelof fluid in the tank 22 drops below the level of the connection of thefluid sensing line 39, no further fluid flows into the line 39 and thefluid in the line 39, the pilot valve 40 and the line 45 graduallybleeds away through the bleeder valve 55 and sump line 56. After aperiod of time controlled by the setting of the bleeder valve 55 thepressure within the line 45 drops to such a point that the pilot valvestem 46 is thrust downwardly into closing position.

When the pilot valve 40 closes, continued bleeding of fluid past valve50 soon causes this valve to close also and the scavenging pump 25 nolonger can draw work ing fluid through the lines 53 and 54 and the checkvalve 32 opens so that fluid is withdrawn from the sump 33 by thescavenging pump 25, and direct recirculation from and to thecounterbalancing tank ceases until the level therein again rises enoughto fill pipe 39 to such a point that the weight of the column of liquidtherein causes the valve 40 to open.

Additional lines and apparatus, some shown in the drawings, as, forexample, an air chamber 58, air compressor control line 59 and otherapparatus not shown in the drawings, is provided for accomplishingconventional controls and operation cycles well understood in the art,the instant invention being solely concerned with automatic fluid levelcontrol instigated by excessive fluid level in the tank and operative toeffectuate recirculation thereof, providing for cleaning, cooling andother treatment of the working fluid as well as eventual lowering of theworking fluid level.

What I claim is:

1. In a hydraulic system for operating a pump, a counterbalancing tank,a working fluid sump, a constantly operating scavenging pump having itsoutlet connected to said counterbalancing tank, a pressure responsivenormally closed pilot valve that is subjected to and opened by extrafluid pressure present only when the contents of said counterbalancingtank exceed a predetermined maximum level, and a second valve opened bysaid pilot valve and operable when open to connect the suction side ofsaid scavenging pump to said counterbalancing tank to recirculate fluidthereto, the suction side of said scavenging pump being connected tosaid working fluid sump when said second valve is closed.

2. Apparatus according to claim 1 and means to bleed away said extrafluid pressure from said pressure responsive valve when open.

3. In a hydraulic system for operating a pump, a counterbalancing tank,a working fluid sump, a constantly operating scavenging pump having itsoutlet connected to said counterbalancing tank, a pressure responsivenormally closed pilot valve having one side subject to air pressure insaid tank and its opposite side subject to such air pressure and to anextra pressure created by fluid in said tank only when the contents ofsaid counterbalancing tank exceed a predetermined maximum level, and asecond valve opened by said pilot valve and operable when 0pc". toconnect the suction side of said scavenging pump to saidcounterbalancing tank to recirculate fluid thereto, the suction side ofsaid scavenging pump being connected to said working fluid sump whensaid second valve is closed.

4. Apparatus according to claim 3 and means to bleed fluid from the sideof said pilot valve subject to fluid pressure.

5. In a hydraulic surface system for vertically reciprocating a wellrod, which system includes a hydraulic cylinder, a rod piston in saidcylinder, a pump in communication with said cylinder at a point on theworking side of said piston, :a counterbalancing tank in series withsaid pump :and said cylinder and an engine for driving said pump, forpumping working fluid from said tank into said cylinder and from saidcylinder into said tank -for raising and lowering said piston, theimprovement in means for controlling the level of working fluid in saidtank comprising, a fluid line connected to said tank at the maximumlevel desired for the working fluid therein, an air line connected tosaid tank at a level substantially above the maximum level of suchworking fluid, valve means connected to both said fluid and air linesand responsive to the balance of pressure resulting from fluid in saidfluid line and air in said air line for opening said valve means, athird line connected to said valve means and in communication with saidfluid line when said valve is open, a dump valve connected to said thirdline and actuated to open by fluid pressure therein, a sump, 1ascavenging pump constantly driven by said engine andhaving an outputpressure above the pressure maintained in said tank, an output lineconnecting said scavenging pump to said tank, an input line having acheck valve :and connecting the suction side of said scavenging pump tosaid sump, a branch line connecting the bottom of said tank to said dumpvalve, and a second branch line connecting said dump valve to thesuction side of said scavenging pump between said check valve and said.pump, said branch lines being in communi cation only when said dumpvalve is open, whereby fluid is pumped from said sump into said tank bysaid scavenging pump when said dump valve is closed and recirculatedthrough said branch lines and said pump to said tank when said dumpvalve is open.

6. Apparatus according to claim 5 in which said fluid line extendsdownwardly from said counterbalancing tank and said valve means islocated at .a level below said counterbalancing tank whereby said valvemeans is responsive to the head of working fluid in said fluid line.

7. Apparatus according to claim 5 and an adjust-able 'bleeder valveconnected to said third line between said valve means and said dumpvalve, whereby the pressure of fluid in said fluid line, and said thirdline is reduced through said bleed er valve.

.8. Apparatus for controlling the maximum level of liquid in a tankunder controlled, constant air pressure in which liquid is rapidlywithdrawn and replaced, comprising a dump valve for said tank, apressure responsive member subject on one side to the air pressure insaid tank and subject on a second side to such air pressure and to anadditional pressure created by liquid in a vertical liquid level lineconnected to said tank at such maximum level, a pilot valve that isopened by said pres sure responsive member in response to the head ofliquid in said liquid level line for connecting said liquid level lineto said dump valve for applying tank pressure through said liquid levelline for opening said dump valve and for holding said dump valve in openposition, and means operable when said pilot valve is open to dischargeliquid creating such additional pressure at a controlled rate from saidliquid level line.

References Cited in the file of this patent UNITED STATES PATENTS1,056,044 Muchk-a Mar. 18, 1913 1,547,429 Ludeman July 28, 19251,766,666 Meyer June 24, 1930 2,393,119 Paasche Jan. 15, 1946 2,586,410Williams Feb. 19, 1952

